The engine immobiliser system is designed to prevent the vehicle from being stolen. This system uses a transponder key ecu that stores the key codes of authorized ignition keys. If an attempt is made to start the engine using an unauthorized key, the ecu sends a signal to the ecm to prohibit fuel delivery and ignition, effectively disabling the engine.

The transponder key coil receives this signal, the transponder key amplifier amplifies it, and then the signal is transmitted to the ecu. The ecu matches the key's id code with the vehicle's id code, which was previously registered in the ecu and then communicates the results to the ecm using sfi communication.
Engine immobiliser system
How to proceed with troubleshootingTrouble in passenger airbag on / off indicator
Description
The occupant classification system detects the front passenger seat condition
and then indicates whether
the front passenger airbag is activated or not through the passenger airbag on /
off indicator
illumination.
The passenger airbag on / off indicator illumination changes dep ...
Oxygen (a/f) sensor heater control circuit
Hint:
Although the dtc titles say oxygen sensor, these dtcs relate to the
air-fuel ratio (a/f) sensor.
Sensor 1 refers to the sensor mounted in front of the three-way
catalytic converter (twc) and
located near the engine assembly.
Description
Refer to dtc p2195 (see page es-292 ...
Battery temperature sensor circuit
Description
The battery temperature sensor installed on the battery current sensor
detects battery temperature.
A thermistor is integrated into the battery temperature sensor, and the
resistance in the battery
temperature sensor changes according to the battery temperature.
The r ...